Recently, a light emitting diode (LED) has attracted attention as a light emitting element having a long lifespan. In the light emitting diode, it needs to control a forward current of the LED in order to maximize the performance of the LED.
Further, a large amount of current instantaneously flowing when powering, i.e., an inrush current, may not only affect circuit elements other than the LED, but also cause the noise. Accordingly, various measures have been devised in connection with the inrush current.
For example, there has been proposed a method for providing a MOS transistor in series to the LED in order to suppress a dimming noise due to the inrush current in an LED driving circuit which adjusts the luminescent brightness of the LED based on a duty ratio of a PWM signal (see, e.g., Japanese Patent Application Publication No. 2010-182883).
Further, there has been proposed, as a technology for protecting a smoothing capacitor, e.g., a technology for preventing the inrush current from flowing into the capacitor using a resistor or the like, in order to reduce damage to a circuit element due to the inrush current (see, e.g., Japanese Patent Application Publication Nos. 2008-125339 and 2002-125367).
Further, there has been proposed a method for providing a current limiting element such as a resistor and a thermistor, or a capacitor at an input circuit, in order to prevent the inrush current when a power supply voltage is inputted (see, e.g., Japanese Patent Application Publication Nos. 2010-177059 and 2005-176002)
However, the above-mentioned conventional illumination devices have a following problem. The problem of the inrush current flowing into the LED does not always occur only when turning on the power. In the LED illumination apparatus including a replaceable LED module, an inrush current due to an output voltage being outputted from the lighting circuit immediately before the LED module is installed thereto may occur at the moment when the LED module is installed to a lighting circuit.
In the installation of the LED module, particularly, in the live-wire work, the attachment and detachment of the LED module are repeated while a voltage is inputted to the input side and the lighting circuit is still operated. In this case, since the LED module is attached while a voltage on the output side of the lighting circuit is not reduced, the inrush current may flow in the LED module due to the output voltage, thereby causing damage to the LED.